<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="../JS/vue.js"></script>
</head>
<body>
    <div id="app">
        <ul>
            <li v-for="item in letters" :key="item">{{item}}</li>
        </ul>
        <button @click="pushClick">+</button>
    </div>
    <script>
        const app = new Vue({
            el: '#app',
            data:{
                    letters:['a','b','c','d']
            },
            methods:{
                pushClick(){
                    this.letters.push('aaa')
                },
                
            }
        })
    </script>
</body>
</html>